Adenosine 3′,5′-cyclic monophosphate (cAMP) plays a role in many diseases and conditions, such as but not limited to inflammation, and other conditions (Lowe and Cheng, Drugs of the Future, 17(9), 799-807, 1992). It has been shown that the elevation of cAMP in inflammatory leukocytes inhibits their activation and the subsequent release of inflammatory mediators, including TNF-α and NF-κB.
It is believed that the primary cellular mechanism for the inactivation of cAMP is the breakdown of cAMP by a family of isoenzymes referred to as cyclic nucleotide phosphodiesterases (PDE) (Beavo and Reitsnyder, Trends in Pharm., 11, 150-155, 1990). It is recognized, for example, that the inhibition of PDE type IV is particularly effective in the inhibition of inflammatory mediator release (Verghese, et al., Journal of Pharmacology and Experimental Therapeutics, 272(3), 1313-1320, 1995). Thus, compounds that inhibit PDE4 (PDE IV) specifically may inhibit inflammation with a minimum of unwanted side effects such as cardiovascular or anti-platelet effects.
Inflammatory diseases such as arthritis, related arthritic conditions (e.g., ankylosing spondylitis, osteoarthritis and rheumatoid arthritis), Behcet's disease, inflammatory bowel disease (e.g., Crohn's disease and ulcerative colitis), psoriasis, atopic dermatitis and contact dermatitis are prevalent and problematic ailments. TNF-α plays a central role in the inflammatory response and the administration of their antagonists block chronic and acute responses in animal models of inflammatory disease. Enhanced or unregulated TNF-α production has been implicated in a number of diseases, for example psoriasis, ankylosing spondylitis, Behcet's disease, rheumatoid arthritis, atopic dermatitis, Crohn's disease, and ulcerative colitis. Tracey et al., 1987, Nature 330:662-664 and Hinshaw et al., 1990, Circ. Shock 30:279-292 (endotoxic shock); Dezube et al., 1990, Lancet, 335:662 (cachexia); Millar et al., 1989, Lancet 2:712-714 and Ferrai-Baliviera et al., 1989, Arch. Surg. 124:1400-1405 (adult respiratory distress syndrome); Bertolini et al., 1986, Nature 319:516-518, Johnson et al., 1989, Endocrinology 124:1424-1427, Holler et al., 1990, Blood 75:1011-1016, and Grau et al., 1989, N. Engl. J. Med. 320:1586-1591 (bone resorption diseases); Pignet et al., 1990, Nature, 344:245-247, Bissonnette et al., 1989, Inflammation 13:329-339 and Baughman et al., 1990, J. Lab. Clin. Med. 115:36-42 (chronic pulmonary inflammatory diseases); Elliot et al., 1995, Int. J. Pharmac. 17:141-145 (rheumatoid arthritis); von Dullemen et al., 1995, Gastroenterology, 109:129-135 (Crohn's disease); Duh et al., 1989, Proc. Nat. Acad. Sci. 86:5974-5978, Poll et al., 1990, Proc. Nat. Acad. Sci. 87:782-785, Monto et al., 1990, Blood 79:2670, Clouse et al., 1989, J. Immunol. 142, 431-438, Poll et al., 1992, AIDS Res. Hum. Retrovirus, 191-197, Poli et al. 1990, Proc. Natl. Acad. Sci. 87:782-784, Folks et al., 1989, PNAS 86:2365-2368 (HIV and opportunistic infections resulting from HIV).
Therefore, pharmaceutical compounds that can inhibit PDE4 or TNF-α, may be beneficial therapeutics. Small-molecule inhibitors have demonstrated an ability to treat or prevent inflammatory diseases implicated by PDE4 or TNF-α (for a review, see Lowe, 1998 Exp. Opin. Ther. Patents 8:1309-1332). One such class of molecules is the substituted phenethylsulfones described in U.S. Pat. No. 6,020,358.
There is a significant need for safe and effective methods of treating, preventing and managing psoriasis, ankylosing spondylitis, Behcet's disease, rheumatoid arthritis, atopic dermatitis, Crohn's disease, and ulcerative colitis, particularly for patients that are refractory to conventional treatments. In addition, there is a need to treat such disease while reducing or avoiding the toxicity and/or side effects associated with conventional therapies.